Power Supply Fan Direction

[amigadave]

What an idiot service tech!  The new PSU's that pull air in usually don't dump the hot air into the case, but direct it out of the PSU into free air.  Often a bottom intake with a rear exhaust, from the ones I have seen recently.

Do you want your Classic Amiga to last longer, or a replaceable PSU and fan?

[amigadave]

+1.  If I'm trying to make a machine last, I add more small fans to blow on the the hot stuff and stir the air.  Then I feel better about using the PS fan to inflate the case.  

The real benefit of reversing the PS fan is controlling dust that is normally drawn in thru the floppy drives, etc.  After the PS fan is turned to blow in, an air filter should be added to the back intake.  It is then a simple matter to clean the air filter periodically (much easier and safer than cleaning out a floppy drive).

Compared to modern CPUs and graphic chips, near stock Amigas don't generate near as much heat.

I think you misunderstood what the OP wrote, as he has reversed the fan to "exhaust" the heat, or blow outward into the room, not into the case.

I would not want the heat generated by the PSU to be blown into any of my computers, so would not do as you suggested by reversing the fan to blow through the PSU "into" the case and placing a filter material over the air intake at the back of the PSU.  I would always add at least one additional fan to blow air into the case and across any heat generating components, with an appropriate filter to keep out unwanted dust as much as possible. This would also compensate for the air being exhausted by the PSU fan, so little or no air would be drawn in through the floppy drive openings, and reduce the amount of dust drawn into the case from anywhere by the PSU fan sucking air out of the case.